A water pressure tank is used in a water supply system to store a volume of water under pressure. Without the pressure tank, the pump would operate each time water was drawn from a faucet or outlet. With the conventional water pressure tank, water is pumped into the lower end of the tank, compressing air trapped in the upper head of the tank. The pressure exerted by the compressed air will then enable the water to be distributed from the pressure tank through the piping system of the building
Over a period of time, the entrapped air in the head of the tank will gradually dissolve in the water, reducing the air volume and resulting in what is termed a "waterlogged" tank. To cure the waterlogged condition, the air head must be restored either by introducing compressed air into the upper end of the tank or draining the tank and subsequently refilling with water.
More recently water pressure tanks have been constructed to separate the water from the air head through use of a bladder or diaphragm, as disclosed in U.S. Pat. No. 4,474,215. The use of a diaphragm prevents the air head from dissolving in the water and thereby prevents a "waterlogged" condition.
The conventional water pressure tank has a water outlet in the bottom, which is connected to the water piping system, and a valve is associated with the outlet to open or close the same. Under normal operating conditions, the valve will be in an open conditon and will only be closed for repair or maintenance of the tank or water system.